[Solved] Excitation of a car alternator

[abaddon]

Hello

Usually the case is the ground, a threaded rod to receive a large terminal is the positive and the other 2 are the excitation and the power of the dashboard voltmeter!

Yes but that's typically the kind of answer that doesn't help me .. I'm not going to plug my alternator into a car. For the connection on the battery, that I have no problem, but I will have to provide the same signal that the control of the car provides to the excitation signal. It is not plugged directly into the 12V battery in a car. In some cases there is a lamp or in other systems it is controlled differently ...

Basically I would like someone to tell me: the excitation signal to be supplied to the alternator is controlled in direct voltage (or in current) and it must be supplied with a value of so many volts (or amperes respectively ).

That's just what I'm waiting for, no further talk ..

but thank you for your answers. If in doubt I will stick to the answer in # 4 of zorglub.

[zorglub]

roughly, if you understood:
supplied a 12 volt voltage source and a capacity of 10 A
the rest will be done according to the load of your alternator.
the more you charge the more intensity A under 12 v
because: 12 v = necessary for the excitation
and as the alternator load increases the excitation (the A's will increase because the U of the alternator will decrease and the A excitation will compensate until you can no longer increase the intensity of excitation and at this moment the voltage of the alternator will drop and you will be at the limit of the power capacity of the alternator
the P of your excitation is given by 12 volts x I ecx (either by the section of your wire)
This is why I explained to you that this section determines the maximum intensity of the excitation

[dirk pitt]

Apart from the connection aspects discussed throughout this thread, I notice that no one has pointed out that it is illusory to want to make electricity on a wind turbine using an UNmodified car alternator.

[zorglub]

see the constraints given by the applicant ........
the rest is another story, because apart from being driven by wind, water, or thermal the problem is the same except for the losses of P from the excitation and the regulation

[abaddon]

thank you very much for everything zorglub. I have everything installed on my test bench and it should be fine. In any case, it is much clearer now.

Otherwise dirk pitt why is it illusory to use an unmodified alternator ??? I never said that I would connect my alternator directly to the turbine ... As zorglub said, you have to read my constraints. If my setup is working properly, I plan to produce a few wind turbines to supply homes in Africa where there is not a lot of equipment on hand.

My reduction will be done with a chain and bicycle sprockets. Because even if it would have been preferable to do it with a notched belt like synchroflex, and well I would certainly have a less good performance, but in case of breakage, it is easy to replace. An unmodified alternator can also be replaced without difficulty. Rewinding is excluded if there is nothing available to do so.

So yeah, I hope my system won't break and hold up for as long as possible, but I predict the worst-case scenario and resonate with it. Perhaps this is not the best solution, but it is the one that seems to me to be the best compromise.

[chatelot16]

the built-in regulator of a car alternator is worthless for a wind turbine

it is a voltage regulator which hopes that the motor is more than powerful enough to provide the power it needs

if the regulator is set to 14v it will send the current it takes to have 14v

the lower the speed of the alternator, the more it will exit strong to arrive anyway at the expected voltage

conclusion for a wind turbine the more the speed drops the more the torque requested from the alternator increases, so it stalls

for a wind turbine, you have to remove the built-in regulator and just send a constant current to the carbon: advantage over the magnet, you can adjust this current to find out with which excitation the current produced is the best

problem if no wind we continue to waste this excitation current: solution use the small auxiliary rectifier which supplies the integrated regulator that we see in the previous diagram, even if this diagram is unfortunately reversed for car with + to the mass

therefore replace the regulator with a variable resistance between the small rectifier and the carbon, and connect a lamp (not necessarily on the dashboard) between the + battery and the excitation to ensure ignition: without wind the consumption is limited to current of this lamp

[Alain G]

Chatelot Hi!

The regulator has nothing to do with it but rather the capacity of the alternator which is often too powerful for the small propeller that we use, the too high power of the alternator causes a blockage!

[zorglub]

the power of the alternator too high

I totally agree with what is said .......
the regulation only consumes the value of the induction coil
especially plan the blades of the wind turbine according to the power of the alternator ... which will only deliver the current intended for the load of the receiver - which means that only the load plays on the output power - a few w loans that correspond to the no-load power it takes to run and excite the alternator ...

[abaddon]

Hello,

Could you come up with some equations to clarify / justify your words?

I am completely interested .. My goal is obviously to keep it as simple as possible. Each part of the wind turbine must be able to be replaced by "ordinary" equipment which does not require modification.

Zorglub offers a kind of shunt excitation, if I use the analogy with a DC machine; it is in my opinion the simplest solution.

I sized a chain drive with 2 stages of sprockets to have a gear ratio of 16 (4 · 4), which allows me to have a propeller that spins at 100 rpm to ensure the minimum power required. If this speed is too high I will increase this ratio, but the higher it is, the more torque will be necessary.

Pél = Ω T - P (frot + wind) - Pcu - Pth

The solution offered by chatelot16 badly degrades the efficiency ... We do not regulate with a resistance ... Anyway, if the wind is not strong enough, then the wind turbine will no longer turn and it is the behavior I expect. [/ quote]

[chatelot16]

you have to know what you want to regulate

the original regulator is made to adapt to a motor which runs at variable speed and has a much higher power

when the engine slows down the governor increases the torque to succeed in taking the power it wants

with a wind turbine it is completely unstable: the slightest drop in speed increases the torque: it is impossible for it to turn at the speed giving the maximum power

this is why many prefer the magnet: constant excitement

a resistance, is a way of choosing an excitation current: of course a power supply with decoupage would be even better

the original regulator does a cutting but its regulation function is not suitable